Posted
by
michael
on Sunday October 21, 2001 @01:17AM
from the too-many-computers-not-enough-time dept.

nexex writes: "Tom's Hardware has a new article with a review of several KVM switches. I have considering buying a KVM switch as I seem to collect/use more & more computers, I feel left with little choice :) While I have several friends who have taken the plunge, they have all spent wildly different amounts on them. Granted price plays a great factor on the features you get, but how do you know which one is not going to end up letting you down? If you end up with el cheapo, you will most certainly end up regretting it, as this device will be carrying the signals of your primary input and output to your systems."

My experience with those switches has all been bad. We had them in an apartment I usda have and they were a pain. And I've had more expensive versions at several jobs and all were also pains. I'd honestly rather just just network to the other machines and run apps remotely. I do keep an extra monitor etc around in case I need to install some hardware on another computer.

I agree with the VNC, however I still keep a KVM in the server room. If you have a lot of servers, and are doing mission critical work, a KVM is better than nothing, and you don't lose so much rackspace if you only have a couple of monitors
The big, mission critical servers are all fit with VNC, as well as have their own monitors, everything else (voicemail,modem and fax sharing, IDS, DNS, etc) are fitted with a kvm. If the OS won't work, neither will vnc, and I'd much rather spend my time fixing the problem than pulling junk out of the storeroom.

KVMs don't belong in the server room, unless you're trying to use NT where it doesn't belong.

The proper way to control your servers is with a serial console server. One cable per box, you can log, and you can get to it from anywhere. In fact, "real servers" (not PCs) shouldn't even need to have video cards installed at all!

I bought a different Linksys KVM switch than the one on Tom's Hardware. I think its called the PS2KVMSK or something. It is much cheaper at about $50 dollars, including all the necessary cables. Ive found it to be a great value and is extremely convenient because it has keyboard-activated switching. The switch is signaled by two quick CTRL key presses. One thing to note though is that if you are playing games that use CTRL frequently, there seems to be a lag between the CTRL keypress and the action in the game. Other than that it performed flawlessly and was definitely worth the money.

I had the same experience. Then I upgraded to the 4-plex switch in the same line (PS2KVM4 [linksys.com]) for about 120 bucks. The keyboard switching is a little more complex (ctrl-shift-alt then a 1,2,3, or 4) but doesn't interfere with gaming.

Yeah, VNC is OK. but it's too sloooow. I haven't had much of a problem using it with Win2K (ie all of our boxes). I use an 8-port switch (can't rember the brand, but it's not belkin or linksys) on my desktopp and it's great. I also use Timbuktu Pro which is really quick, but often it has problems authenticating domain users on client machines which is a royal pain-in-the-arse (tm) (ugh, i have to actually get up and walk the 10 feet to authenticate myself on the machine...)

We actually use a serial console system for most of the ~200 servers in our machine room (we have an actual monitor/keyboard/mouse on a little cart we wheel around for when we need it, which is rarely).

Anyway, to the point, you can make a simple little loopback plug for the keyboard and/or mouse if the system is fussy about that sort of thing.

My personal experience is from a while ago with extremely cheap switches, but I do remember I got things like ghosted video (not always, it seemed to depend on which computer was hooked to the switch and so on). As the article says: In our testing, we found that it was more important to use good quality cables and follow the instructions in the manual to the letter.
. My solution? I got rid of all the computers except one. But I doubt that would be of interest to the average slashdot reader;-).

I've been using the IOGear 2-port KVM switch reviewed in the article for several months now, and I have to say I love it. I use it to share between XP and Linux, and neither machine has ever had a problem with the USB devices. I did run into a slight problem with the video causing snow and jitters in X11 (no problems at all in XP), but adjusting the modeline (dumped via xvidtune, changed the polarity of the hsync) made the problems disappear. For anybody who wants to get away from PS/2 systems, or uses Macs, I really do recommend IOGear.

The only thing I could wish for is the OSD/hotkey support of IOGear's 4-port model, but I can live without that. Also, Tom's price was a bit high. I bought mine for roughly $100 at a local computer store.

I have a 4 port PS/2 IOGear KVM and I've been quite happy with it. I haven't had any problems with it with X11, but there are occasions where it won't recognize the hotkey sequence to switch machines. It ususally happens if the current machine dies due to the Nvidia driver locking up. Then I have to use the button on the KVM to cycle the machine being displayed.

At my previous employer [wego.net] I had one of these to switch between my laptop (Sony Vaio Z505, mmm) and my tower (HP Kayak, bleh). I'm almost positive it was the GCS124U [tomshardware.com], but it didn't have the OSD stuff they mentioned in the review. I remember that the one thing which annoyed me about the KVM was that there was no way to jump past the 2 empty slots, and there wasn't any way to switch via a keystroke or anything but the Big Button. Then again, I was running Slackware, so maybe it required some sort of special software. Other than that, it was a really solid unit, and I highly recommend it.

You can see my setup [quadium.net] right before they laid us all off. And of course they kept the KVM and the shiny laptop...:(

until you have to replace hardware in one of those, and then you will have to move junk around (keyboard and monitor, or the system itself) when you bring it back up (ie, having to change the bios settings if you add a drive).

I just went through this with my headless firewall. I sure wish I had a KVM for the machines then. Then again, that's about the only time I would ever use it, so I guess it would be wasted money for a little bit of annoyance.

My experience with workstation switches from several different
manufacturers is that they are very expensive (around $1200 for a quality 8 pt switch) and that they have siginificant maintenance issues.

Where I work, we use a couple dozen switches on many, many server machines, and are RMA'ing them all the time because they simply break down quickly. Mice are the first to go. Then monitors. Maybe we're just unlucky. Personally, I feel that if a piece of hardware is dipsosable, it should be given a disposable price.

We have to have these for space reasons, however, so we keep plugging away at trying to keep them working. Recently, we've been reducing the costs associated by picking up several nice switches from dot.bomb auctions. We're getting them from anywhere between 10 and 20%. For high-maintanence hardware, this is *much* better than paying full price.

The guys at Inova [inova-inc.com] have a KVM switch not reviewed in this article. In addition, they claim that it doesn't just switch the KeyboardVideoMouse, but all your silly devices. There's a small, pleased review of it here [internetwk.com].

I use 8-port Apex KVM switches at work, and they have some nice features; they also have a few flaws. These KVM switches arent the cheap ones found in this review, but if your looking for higher end equipment I might be able to give some useful nformation.

The switches are only KVM, no sound, no USB. To change screens, you press the print screen key. It brings up a menu, and you can choose between any of your machines. The machines can all be named, so you know exactly what machine you are going to. Another nice feature is that you can chain them together for more than just 8 machines on the switch. My only real complaint is that sometimes the menu doesnt get erased when you switch machines, so you have to bring it up again and get rid of it. I havent had any problems with screen resolutions, keyboards or mice. Definitely worth looking into for a setup with more machines than two.

I'm surprised Tom is so exciting about audio switching. Most decent speaker setups will take more than 1 input signal, so you can have both (or more) boxes hooked up to the same speaker at once all the time. It's nice to be able to play a CD or something from my other box while I'm using the first's drive.

Well, audio switching is nice so you can have one set of speakers shared between all of the computers. Otherwise, what's the alternative?

Ideally, KVM switches would have audio inputs and be selectable between 'mixed' (where all the audio inputs would be mixed, so you can achieve what you proposed) and 'switched' (so it only selects the audio for the current computer).

I think slashcode has decided to implement session-based comments. In order to post a comment, you first have to load comments.pl with op=Reply. The form contains a hidden element called 'formkey' along with the other standard elements.

I assume these are entered into a database and given some sort of expiration time. If you don't post the comment within the allotted amount of time your form key expires.

Haven't tried enough things, or bothered to read the slashcode, to find out what it's doing exactly, but it seems like a pretty reasonable way to cut down on autoposters.

Until they figure out this regexp:

/NAME="formkey"\s+VALUE="(\w)"/

$1 contains your formkey, now you can go crazy. Slashdot will then start populating the form with hidden, invalid formkeys, commented out with HTML.

The trolls will then start using honest-to-goodness HTML parsers to autopost, and then slashdot will be screwed again.

I've experienced that too. (I didn't try restarting Moz though.) I run Moz 0.95, I just switched from 0.9 and before that I never had any problems.

I was even doing the "right thing" and filling in a bugreport at SourceForge. Naturally it required that I had a SF login to post the bug. And it told me that AFTER I had filled the bug out. An-noy-ing!

I agree! x2x has been a godsend for my computing setup. Not only does it let me move my mouse/keyboard across multiple displays like I had a multi-headed machine, but it does cut 'n paste too! I used to have an unmanagable keyboard mess on my desk. Now I just boot the boxes, then stow their keyboards aside. (then again, I've got 3 monitors in front of me on 3 different boxes running 3 different 'nix OSs... Isn't X wonderful?)

I'm going to have to take a look at some newer 2-port KVMs. Those I've tried in the past have never lasted long -- not that they've worn out, but they've worn me out with the hassles of setup, troubleshooting, etc. I use 8-port KVMs in the server room at work and have no gripe about them, but the 2-port switches have been a different story entirely.

I've been using a Belkin OmniCube 4-port kvm at my desk for almost a year now and it's been great. I think I paid about $130 for it, but I've recently seen it for nearly half that on sale at the various superstores. I have also chained an older Belkin OmniView 2-port kvm off it and it works fine.

KVMs are no longer just the domain of the NOC... for those who prefer Linux, but need a Win2k or 98 (ugh) box on demand (or anything else for that matter) a kvm can be a huge plus. It's also allowed me to save space (got rid of 2 extra monitors on my other desk).

The OmniCube has a nice shortcut... double-tap scroll-lock, then hit the number of the box I want and it comes up. This has allowed me to leave the kvm on the floor behind my desk, with all the cables.

One thing to consider... I use a high resolution and a high refresh rate on my monitor... if you want 1024x786 @75Hz or higher, you'll probably have to shell out around $25 for a high-end vga extension cable. PS/2 extensions can be had for under $5 ea, and lower-grade vga extensions are easy to find under $10. Just something to keep in mind if you are on a budget.

Only negative I've found is that I need to have the Win2k box selected while it boots, otherwise the wheel mouse isn't detected... the rest of the mouse works, just not the wheel.

Anyone know if it's possible to get my Sun Type 6 USB keyboard to work on my old intel PS2 system, through a switch? Is there a USB->PS2 converter that works with the Type 6, that I could connect on the switch output to that PC? Any ideas if I would run into problems switching between them, and losing keyboard? Same question regarding Sun's Crossbow USB mouse. I really wouldn't mind all that extra desk space.

Toss a USB expansion card into the intel box, pick up one of the IOGear USB switches in the review, and be done with it. PS/2 is outdated. USB is the way to go for these low-bandwidth input peripherals.

I had a Belkin 2-port for a long time that worked nearly flawlessly. The only problem I ever had with it was switching away from an X session and then going back would cause the mouse to go haywire to the point of needing to restart X. Not sure if this was the fault of X or the KVM switch, but either way it was annoying.:-)

A few months back I was looking through uBid.com and found a 4-port KVM that had plenty of features (more than the Belkin, at least) and even included 2 free cable sets. I had never heard of the brand (Genie), but I figured at only $100, it was worth a shot to get all my machines hooked up to the KVM and thus ditch an extra monitor. And luckily enough, it has performed flawlessly. It still irks me to remember how much I paid for the original 2 port Belkin (almost $300 a couple years ago) now that this "cheapo" one is working so well, but its also good to see the good features and stability of the higher end KVMs coming to the lower end of the price range.

Better then this would be a unit that lets you plug the system(s) in to a "collector box". This would then run a single cable to a second box that would split up the signals to the original cable layout again, thus enabeling you to keep your servers where they you can't hear them, as well as letting you operate several box's from one set of keyboard, mouse and monitor.

Background: Good KVM's are expensive. Cheap KVM's are awful. Many monitors now have a built-in high quality A/B switch. Many KVM users spend 95% of time on a workstation, and occasionally have to flip to a "headless" box to make a BIOS change or something.

Why not buy a cheap KVM, attach a cheap keyboard to it, and plug it into input B on the monitor? Then most of the time you have high quality video from the workstation to input A. When using the KVM, you probably don't care about quality. Of course, there is the danger of typing on the wrong keyboard.

Personally, I just use the monitor A/B both at home and at work. The B cable goes on whatever box I'm fixing/setting up at the moment. Once the box has networking, there is no need for KVM.

I have an OmniCube (2-port; no USB) and I love it. Once in a while I get a blank monitor after hitting the scroll lock key twice and the up/down arrow key to switch to the other computer. I noticed my monitor (IBM P72 17") says it lost the video signal. I have to turn the monitor off and then on to make it come back.

I did some research into this a couple months back, and at the time (last spring-ish), Belkin did not have a solution for USB-only KVM switching (I actually called them up and asked). Oh, you could certainly plug a USB mouse and keyboard into the switch and use that, but you won't get any hotkey switching, and might even have other problems if you don't have at least a PS2 keyboard also plugged in. I'd suggest the IOGear boxes listed in the review (the 2-port version is very basic, with no OSD or hotkeys, but the 4-port version makes up for that).

Why bother with expensive KVM switches? I looked in to getting on these while back when I added a 5th box. First of all, the cabling is usually not included and can cost just as much if not more than the switch itself. Anyone who has a lot of boxen lying around also tends to have a plethora of old keyboards and monitors. Even if you don't why bother with a switch when you can just SSH in or for windows use winxp remote desktop? I guess KVM switches are great in situations where space comes at a premium or you have a lot of cash burning a hole in your pocket.

I've had this for over a year and I've never had a single problem with it. We struggle with the OmniView and others at work all the time, my Linux boxen always lose mice, or experience pointer wig-outs on the others, but never on the Iogear. It also has the best monitor quality I've seen so far.

Use VNC [att.com] (free; open source; multi-platform). If you have the multiple machines networked on a resonable network (10 Mbps is fine, 100 Mbps is completly lag free -- even works OK through cable modems). Then all you need to know is the IP address of the machine, and you get an instant view of the desktop and you are able to move the mouse around, use the keyboard, etc. It's kind of like PC Anywhere, without the bloat and it's cross-platform and performs very well. If you have a DNS server, you can even assign computers a name.

No switches or cable to deal with, and best of all you can use multiple machines at the same time (e.g. at a resolution of 1600x1200 with 800x600 VNC windows), and also use your main computer. With KVM switches, you physically switch everything over, which when done many times risks damage. Not to mention all those cables going to all the different machines to do the switching.

KVM is a thing of the past, right next to the 300 baud modem rack hosting the ASCII art BBS, when you needed to view the screens of several 386's. It also doesn't make sense, to say, use a KVM switch for 10 computers. However, with VNC you have the limits (on a private network anyway) of the entire IP dotted-decimal.

That doesn't work when you have to reboot and make a bios change. I can do all of that stuff using X11 forwarding, and it works better. You probably don't want to play games like half-life that way either(I don't use everybody's quake example..because THAT RUNS NATIVE ON LINUX, YOU FOOLS!)

Some time ago, I was looking [google.com] for a solution to a cross-platform KVM integration issue, tying some SGI gear and my PC to a single console.

My problem arose because the SGIs use a sync-on-green signal through 13w3 plugs, while PCs typically don't. I was lucky in that most SGI kit made in the mid-90s and after uses PS/2 mice and keyboards. I further complicated my situation by wanting to tie the sound from the different boxes together.

Eventually [google.com], I bought a Belkin OmniView SE 4-port PS2 KVM switch, and some adapters. To handle the sound, I bought a cheap Fostex digital mixer from musiciansfriend.com[1], wired it all up, and today, I am the proud owner of a monstrous rat's nest of cables and boxes that pipe sound from multiple machines into one set of speakers.

It would have been a hell of a lot easier and cheaper just to buy three sets of speakers. I'd be careful when evaluating a KVM+Sound switch, verifying that sound is mixed from all channels, as it is almost a necessity to be able to hear output from a non-focused computer.

As it is, I'm ecstatic about the Belkin gear. I have the OmniView SE here at home, and the OmniCube at work, and with decent cables, I can drive the monitors at 1900x1200 without any difficulty. I found this to be just about the most important piece of the kit -- with cheap cables (the kind you can buy for $10), the video starts bleeding and exhibiting static above VGA resolution. Don't waste your time with the cheap cables, spend the extra $10 or so and get the decent ones.

[1]: I am intentionally not making that a link because the bastards are almost as bad as x10 for daily emails once they have your address.

Here's how it would work. You mount the box on the back of your server unit and connect your power and reset buttons to the unit and connect the unit to the reset/power jumpers on the motherboard. You stick the light sensors near the respective LEDs. You wire up the KVM to the unit and optionally plug the local devices into the unit.

Now, the unit is a little linux box that takes the input and sends it over the network (now we're using VNC) to my remote session. The bonus is that I can still see the unit if it's crashed (the VNC service or the whole dang box). I can boot into the BIOS and make changes. I can run utilites and so on from DOS sessions. Plus, I can click a button and reset the box, or power it down. If I connect to the session and see no image, I can see if the power light is on or if there is any hard drive/network activity.

I can think of about a billion times in my techie lifespan that I've wished for such a device. Yes, I know there devices you can use to remotely power off a computer. Yes, I know I could setup a webcam to monitor some lights. Yes, I know VNC gets me most of the way there.

But it's not cost effective to buy one of these for each server. I would rather have one box that could control 4/8/16 boxes. It's just a standard KVM with some extra inputs attached to its own dedicated Linux box!

So please, Linksys, Belkin...whoever...can't someone please build this, or show me a link to something like this?

Oh, and for bonus points...how about another connect to allow this network KVM to function as a floppy boot device? IE, I would transfer a floppy image (say a BIOS update or a Ghost boot disk) to the KVM from my workstation, reboot and have the remote system boot to the "Floppy" on the KVM. Then I "eject" the floppy and reboot into the normal mode.

I forgot that floppy swapping is another big reason I've had to make wasteful trips to the server room, which I would like to eliminate.

Well, a couple of things that probably aren't exactly what you're looking for, but may help:
There's a product out there called "crystal cube" which has a small "computer on a card" and then runs CAT5 out to your desk carrying video, keyboard, etc. etc. That's still a one-to-one, though.
More to your liking may be a product from Belkin. You can hang your workstation off the KVM via CAT5, so the KVM can be in the server room with you at your desk. They also offer a dual-head KVM: two people working on any two of the machines on the KVM. They have some good stuff, and the quality has been OK from my experience. We're not using their so-called hi-res cables and the video is acceptable for server maintenance, but I wouldn't necessarily recommend it for long-term used.

I had one demo'd here at work. It was being resold by WrightLine, the rack enclosure people, but was available seperately from the manufacturer.

It was tres expensive, though -- like thousands of dollars, *but* with the client you could connect to any machine that was connected to it over a network and get hardware-level control over the machine -- BIOS screen, dos prompts, totally seperate from the OS running on the machine.

The magic was their ability to do real-time video compression of the hardwired systems displays. The client app that could connect to the switch could also resample a hi-res screen to fit a lower res screen, as well as send special keystrokes so that you could use cheapie switches daisychained off of the expensive one.

It had limitations, though -- the client software was licensed (cheap money grab attempt), and it was a bandwidth pig. The guy that demo'd it didn't think it would be practical to control a system via dual-channel ISDN and barely practical over broadband connection. And it was REALLY expensive, I seem to remember a price in the thousands for the 8 port box, cables and a 4 client license of the remote-use software.

What surprises me is how dumb the video is in even non-networked high end KVMs. Why isn't there an option to do picture-in-picture? Or tiling all connected systems on one screen? With a good hi-res display and resampling, you should be able to monitor (maybe not use 6pt windows, tho) multiple systems at one time. There's loads of video tricks that get used in even the low-end TV world that really ought to be in the KVM world.

There are two types of KVMs, active and passive. The active ones have various and assorted circuitry inside and possibly associated software. The passive ones just have a multipole switch inside. This type would be fine for what I need *if* I knew what to add in (as in solder, etc) to keep the computer being switched away from from noticing that it no longer has a keyboard and mouse attached (and of course there's that need to detect a PS/2 style mouse--IRQ 12-- on startup). If anybody knows just what's needed, please feel free to speak right up.

Oh, by the way, how about this quote from the article--"I could go into a long winded explanation of how KVM switches work, but, to be honest, I found this to be boring, and I am sure that most of you would, too, so I will spare you the explanation." If he really could do that, why can't he go into a concise but complete explanation?

I've been using a KVM for years, starting with a small cheap box that just switched the monitor signal to finally graduating to the linksys ProConnect 2-port switch.

I don't profess to be an expert on KVM switches, but the Linksys has worked decently for me. It has this feature where it listens in on your keystrokes and switches computers at a double tap of the cntrl key. Annoyed the hell out of me in quake until I figured out what was going on (like most computer students I chucked the manual the instant it came. ..oops).

However, despite this, its VERY small, cheap (check it out here [buy.com], comes with cables), and I'd buy another one in a minute.

One test that Tom didn't do is the Quake 3 test. I had purchased a KVM switch earlier this year and it worked ok. I decided to throw everything I could at it to try it out before I decided to keep it.
So I tried playing quake 3 on it, and the thing crawled. My usual 30-50fps from my geforce2 mx turned to about 3fps! So I packed the switch up and sent it back. Ever since that expierence I haven't been too willing to throw away more money on shipping costs to try out another KVM.
For the cost of a KVM switch, I think I'd rather just buy a $150 17" monitor, $10 keyboard, and $10 mouse. After all, that's all I'm using anyway.... no compatibility issues with that either.

So I tried playing quake 3 on it, and the thing crawled. My usual 30-50fps from my geforce2 mx turned to about 3fps!

I use a Linksys ProConnect 4 to switch between my gaming machine and my work machine (and soon a third box). I've had zero problems with gaming performance. I play games on it very regularly (including Quake 3). My score in 3DMark2001 was completely unchanged through the switch (I use a GeForce family card as well).

One thing people in this situation might want to try (specifically, if you have a GeForce family card) is to get into the GeForce Additional Properties dialog, go to the OpenGL tab, and make sure the Vertical Sync option is set to "Always Off".

Of course, I also had to spend a small fortune on cabling to get acceptable video quality, but the reclamation of desk space was well worth it!

In the article, Tom has concentrated on go/no-go tests.
In a product that can influence picture quality tremendously, I would have liked to see something more than "It... produced a good picture " (with no mention of the resolution tested) in case of the CS-USB21H , or no mention of picture quality at all in case of the GCS124U KVM .
It would have been really helpful to see characteristics like 'amount of reflections' or 'actual measured bandwidth'
This would have helped me more on deciding which unit is right for my purposes than describing the computer systems that were used in detail. What is the use of specifying the brand of CD-writer or the amount and brand of RAM that were used? I cannot imagine that these have any influence on the performance of the KVM switch.

Yeah, I was seriously wondering about this as well. Simply switching between boxes with different resolutions is more a test for the monitor than the KVM. How about running a cable straight to the monitor, then comparing that to what it looks like when the KVM is inserted? Even with high quality cables there is still a healthy bit of attenuation to the signal on most KVM's.

What is the use of specifying the brand of CD-writer

I liked how we got to hear about what case they used for the PC's. How about something useful, like how many buttons were on the mouse? I've got a Logitech trak ball here with 4 buttons, and I know many KVM's simply won't support that.

From my own testing, Cybex has been the friendliest to my 4-button mouse, but with poor video quality. The Linksys I once owned had great video quality, but no support for button #4.

OK these 2-way system our fine and useful
for home usage. But for a real server operation
you good do with many more connections.

Our rack of 10 linux boxes is connected to
the head, by two 8-way OmniView boxes ganged
together, this system work fine, except that the
time between press the scan button of the box,
before you can press it again is a few seconds,
slightly annoying when you need to get from box-2
to box-10. A hold down repeat or numerical keypad
to select box would be nice.

What do you KVM does anyone else recommend for
heading a rack of boxes.

What is it with all these people using KVMs on their servers? There's a MUCH better, more managable, and more "proper" way do to this... Ever hear of a SERIAL CONSOLE SERVER? Yes, that's right, UNIX can do the system console over the SERIAL PORT! Much cheaper, lets you do console logging, etc. In fact, real servers don't even need to have video cards installed at all! (not talking about PeeCee hardware here)

For heading a rack of boxes, I'd either recommend an old machine with a big multi-port serial board and a program called "conserver", or one of those embedded serial console server solutions (i.e. PortMaster)

At home I used a Iogear $60 USB KVM that works really well for video but causes all sorts of problems with the USB keyboard setup under Linux on my Tiger 133a (There is a problem with linux on the via chipsets that cause it to not be able to use USB devices with SMP enabled)

At work we use Aten Masterview switches wich cause all sorts of problems. They meerly move the monitor, keyboard and mouse connectors through solid state switches. This is anoying because when a system reboots you get keyboard errors and things like that. (Yes, I know most BIOS's can disable these warnings.. but nto all of them =) We are slowly switching over to the Cybex A400 series KVM's. These switch boxes allow us to connect up to 48 computers into a single monitor/keyboard. (several 4 ports into a 16 port) They include on screen display and lots of other features. One really nice thing is that they only use a cat five cable between the switches and not normal keyboard/mouse/vga cables.

The major draw back to these switches is that they cost a LOT. (up to $20k for 48 systems) They do however display really well and flow the keyboard and mouse across all systems. They also can be setup to give users access to some systems but not all. So you could give your user the ability to access the workstation/test system next to the server but not the server itsself. Its really nifty =)

(And of course, this review comes our TWO days AFTER I purchase a new Belkin 4 port E-Series switch box =) The thing hasn't even gotten here yet!

Test 11: We unscrewed each box and removed a
vital component, reconnected the PCs and filmed [streamgate.de] the results.

[Banner Advert for Belkin]

As you can see every for box expect the
Belkin, this resulted in the monitor exploding.

How irresponsible of the other manufacturers not
protect there products against sabotage. This
could have your childs monitor exploding. Think of
the damage the shards of glass would do to his
innocent little eyes.

what kind of./ reader would buy a 2 port kvm, limiting oneself to 2 boxes? was my thinking. folks have said almost everything about the belkin, which works great for me too. only little annoyance is that the keyboard shortcut (quick taps on scrlk + number 1-4 of computer you want to jump to) results in the number bring typed into whatever window is open on the linux box. so now an then an extra '1' throws a wrench into some code (once, an invoice, but it didn't get me any extra cash). there's probably a way to fix this but...laziness

The Belkin OmniCube is crappy, doesn't support high resolutions and decent refresh rates, and then it broke so that I could only get signal to one of the computers. Yay! A signal degrader instead of a KVM. The place I work at also has larger Belkin KVMs and they're not working like they're supposed to. Cheap and a waste of money.

The Raritan SwitchMan is exceptional, and works wonderfully. However, you need to use special cables as it wants Male to Male instead of the usual Male to Female. The cables aren't cheap. But I can run high resolutions at 85Hz, and there are some programmable features. You can also chain them together. The more expensive Raritan models support some even more interesting features. The only drawbacks are the somewhat more expensive price, and lack of support for Macs and USB.

I've also found that in addition to switching the keyboard, monitor, and mouse, I want to switch the audio. So, I purchased a Nady MM4 mixer from Musician's Friend (about $80 after shipping) and now I can also mix four audio sources to my Desktop Theater 5.1 sound system.

Something else I think should be mentioned is that you don't have to use KVMs (or the audio mixer) only for computers. I have my Dreamcast plugged into the Raritan KVM and Nady MM4 mixer for use with the VGA output. I plan on getting a PS2 and sending it to the same port of the KVM via a breakout box and video switcher (and my N64 at that point as well), or to a TV tuner card and then to the monitor, plus it's audio signal to the mixer.

The only thing I really want but haven't seen anywhere is the ability to use Macs and PCs alongside the gaming consoles. You can't really interchange Mac and Windows keyboards, but I'd love a KVM that I could do that with. If it could just interpret the Command/Apple key on the keyboard as the Windows key, and vice-versa, then I could put them all on one keyboard, monitor, and mouse.

I am almost 100% happy with it. The only problem is that it seems to have some problems passing the mouse to IBM Thinkpads, and no OSD. Also the keyboard hotkeys (Shift-Alt-Control then number 1-4) is a little clumsy, and the tiny unit doesn't sit very well because it has cables coming out ever side.

Can anyone tell me if they have solved the problem with some IBM gear (in particular IBM Thinkpads). The problem is that they don't get the mouse signals from most of the KVM switches I have tried, and I can't work out why. This means that you have to have a 2nd mouse, or use the trackpoint on the Thinkpad keyboard, which is a real pain.

The makers of my switch (ATEN) have this as one of their FAQ's [aten-usa.com] on their site, but I have followed both of the recommendations and neither work.

Can anyone tell me if they have solved the problem with some IBM gear (in particular IBM Thinkpads).

This is a quite common problem w/ laptops in general. I tried three different Dell laptops through my Linksys ProConnect 4, and none of them recognized the mouse through the KVM, and I've heard of others (Gateway, IBM) in the same boat. Best I can assume is that something is funky about the laptops wherein they want to disable the internal pointer for the external one, and must be using something non-standard to detect the mouse presence. Having the KVM tuned to the laptop on bootup didn't help, either.

I can't belive they left out Avocent [www.avocent.comtarget]. The company is a recent merger between Cybex and Apex and their products are great.

I've been using Cybex stuff for a couple years now, I have one at home, one at work and 2 in my sever room. They work flawlessly and the 2 port Switchview with cables is $169.

About the Blekins, the reviewers didn't have any trouble with them and I see positive comments as here as well but IMO, they suck really bad. I had one at home that was junk. The last company I worked for had one for every developer and ended up replacing all of them, they were just terrible.

Needing to multiplex a console between two machines is somewhat silly. I got into KVM tech when 8-16 machines were involved. My company use Sybex 8 port units and they worked well. You could even slave the units to handle more servers. At home, I have a bunch of PCs (4-8) so I took the plunge with a 4 port OmniView unit (1998). That broke within 18 months. I then replaced it with a 4 port Linksys unit and that seems to be working very well. WinME can see my wheel mouse and linux can see that I have some kind of two button thing. No complains.

The warning about cable management should be taken to heart. I'm nearly drowning in the buggers. I suggest getting a metal rack for storing your PCs, printers, scanners, KVM unit.
Use zip-ties or velcro strips to secure the cabling. It's worth the investment. When the cables were loose, my cat starting *eating* through them. That's a different rant...

As for mulitplexing sound, get an audio mixer. I have a Mackie 1402 and love it. My speakers
(Labtec Edge 418 [labtec.com]) are plugged into the mixer, as are the PCs. I can even have my tape deck hanging off the mixer. This mixer/PC system has replaced my stereo.

One last point: I don't have a TV either, just a tv tuner card. Single appliance convergence? Already there!

Here at work we all have BlackBox 2 and 4 way KVM switches. They're very sturdy, and what's most important, incredibly reliable and perfectly compatible with both Windows NT/95 and Linux. I use a Logitech scroll mouse which works fine with NT, and works as a 3 button mouse under Linux, perfectly.

The only problem is, I hear that these Balckbox switches are expensive. I don't know, company paid..

I was messing around on my own machine once, and it was run into a KVM, but the setup was skewed... Nothing on my screen was moving, so I figured it was stuck. So I did a keyboard reboot. Our largest client's colocation server next to me goes "...beep." Whoops.

i've had it for years, it's fine for windows, if you have any *nix at all it sucks shit, having to unplug and replug in the keyboard every time you switch between consoles sucks, it doesn't work with my logitech trackballs (the only mouse i will ever use) at all, requiring me to have seperate ones for each of hte 3 computers using the switch.. essentially teh only thing it does well is switching video.. i can't speak for the latest model that he reviewed (and reccomended as the best one) but mine (f1d094) is a piece of shit.

/.
I also use this model and am reasonably happy with it. I use a generic AT keyboard and a single 3-button logitech mouse to drive a dual-boot win98/RedHat 7 box on port one, a RedHat 6.2 box on two, a 486-based dual-boot Freesco/Smootwall router PC on 3, and the fourth port is connected to an extremely long custom cable that I use for beowulf nodes and boxes ripped apart on the workbench as necessary. I used to use a MS "Natural" keyboard on the Belkin until I spilled something nasty in it, and that worked OK too.

HERE'S THE PROBLEM: You must follow this procedure when you set this thing up, or you will get the symptoms you describe.
1) Plug all cables into Belkin.
2) Apply power to Belkin.
3) Boot machines in any order *** BUT *** do not *** EVER *** switch consoles if any machine has not finished its boot sequence!!!!
4) You may now switch freely, and you may turn machines on and off as you wish as long as you remember never to switch while any machine is booting up.
5) Go forth and prosper.

This little gotcha really bothered me because I am the type of dummy who "saves time" by booting everything at once and switching about during the boots to spot-check for clean startup message sequences. You don't want to know how much time this "time saving" habit cost me before I got around to reading the damn manual.

/.
The problem with a mac is the weird keyboard (Apple Desktop Bus I think it is) and mouse interface my macs use. I can adapt the video to VGA easily with a cheap little adaptor, but the ADB to PC interface is blindingly expensive even though there are chipsets available fairly cheap.
I keep intending to build one myself from the chips, but I am way out of practice at that sort of thing:^( and have little time:^( so I just switch the video and shove the mac KB and mouse off to the side most of the time.
If anyone runs across a cheap solution to this problem PULEEZE post.
--Charlie

My KV (no M, they were out of ones with mouse ports when I bought it so I have 2 mice) is an extrememly simple switch that basically looks like the printer switches you can get at Best Buy. It has 5 VGA and 5 PS/2 ports on the back (one pair goes to the monitor and keyboard, the other pairs go to computers) and a toggle switch on the front. I simply move the switch to whatever computer I want and the signals go through. I don't think I paid more than $20 for the thing, and it's been working for more than 2 years. I don't know much about the brand; I bought it at a small computer show. It says it's a QVS Heavy Duty Dataswitch. Since I've never really had any problems with the switch, I haven't cared all that much.

My biggest problem is the fact that I can't seem to find any decent video cables, so I get a subtle shadowing effect at high resolutions. It's bad at first, but I've learned to live with it. I suspect that if I got better cables, it would go away, but everywhere I look that even bothers to sell male to male video cables sells the same type of crappy looking ones that I have.

I've looked at some of the more expensive switches, and I really couldn't justify spending that much, especially when my little switch does everything I need. And having two mice really confuses other people when they try to use my computers:)

No people, VNC is not a magical kvm that replaces the need for KVMs. Nor can it be used as one. It's more of a hack around using kvms, or for those who can't afford actual KVMs (which is not something to be sneered at - KVMs are really expensive).

1) If networking dies, VNC dies.
2) If something in the operating system goes really funky, you might not be able to VNC into it.
3) Additional system overhead.
4) If the system hard crashes, you can't see what the last error message says. Even linux and solaris boxes panic.
5) Saying that everything should be managed from a serial port is misguided. A GUI shouldn't be so dismissed, there are lots of WinNT servers out there with is mostly graphical driven, and there are X apps and the Netware console screen that you can't see through a serial port. Likewise, what about a whole bunch of workstations, probes, monitoring machines, and other commodity x86 hardware?
6) You can't see POST and OS loading messages with VNC.

VNC is okay if you don't have any cash, or perhaps in your house. It's not the greatest solution in the world, and can't replace the need for a KVM. I wouldn't advocate using it as a kvm in a machine room.

KVM over IP [kvmoverip.com] is a great solution for heterogeneous data centers. No software needs to be installed on the servers, and it works in conjuction with regular analog KVMs.

We have the DS1800 from Avocent, which connects to 4 ordinary Avocent KVMs on racks. We use them to administer the NT/2000 and Linux servers. The system works great, and VPN'd over my Cable modem is pretty close to being in the room. The downside is the the software used to interact with the KVM Switch (DSView) is Win32 only.

And it does cost quite a bit. To support 41 servers, we spent just under 16K. The system scales pretty well. We've only used half the ports on the switch, and can add addititional racks as they are needed. Up to eight KVMs per switch, with up to 64port KVMs supported.

A little over a year ago I bought a Dr. Bott [drbott.com] 2-port USB KVM from DevDepot [devdepot.com] for $139. Dr. Bott stuff is more Mac-friendly than most-- the KVM has dual video ports (i.e. Mac DB15 and PC HD15) for each position on the switch.

All cables are included with the switch, and the video cables have one end HD15 and one end DB15-- no matter how you have to hook your computers up, you can get it done by just swapping cable ends, no video adapters needed.

Contrast this with Belkin, who charges out the ass for everything, cables are extra, and sometimes requires a separate box to provide Mac connectivity, resulting in an ugly mess of tangled cables. Sure, the Belkins are electronic while the Dr. Bott is physical, but I'd rather pay less and wait a few seconds for my keyboard and mouse to be detected when I switch (and have a much neater-looking work area).

I just bought a Belkin 4-Port KVM switch a while back for $100. There is a huge, huge difference in prices between stores. My local Fry's and Micro Age carried the same one for around $270. After cruising Pricewatch I bought mine at Harmony Computers [shopharmony.com]. Gotta love the Internet.

My wife taught me a great phrase: "you don't ask, you don't get". While employed in a server environment, we were updating all the Cybex switches to the latest and greatest model. I asked if I could take one of the old ones home, the boss said "sure." I draped sixteen 10-foot cable sets over my shoulders and carried the two control boxes right on the train that very night. You just have to ignore the funny stares:)

When the company was throwing out some old Digital DECTalk hardware, they offered it to me "only if [you] can take it home tonight." I replied, "it's a good thing I drove!" I got a 5 foot rack with four 8-channel DECtalkers designed to convert serial text into speech audio out over phone lines and return DTMF keypresses back to the server over the same serial lines. I gave away 3 of the 4 talkers, kept the 5 foot rack and two serial sprayers. I thought it would be perfect for 8 channels of hardware text-to-speech in my home automation setup. (Its the same hardware used at NOAA weather radio.) Too bad the terminal server talks LAT. Linux will support it soon enough, if it doesn't already.

A friend recently went through a big cleaning in his server environment and made off with two active KVM switches. His are better because my passive ones don't support higher than 60Hz refresh. Mine are just fine for Linux consoles and VERY light duty X work.

Finally, during a really big spring cleaning, I brought home a Digiboard PC/8. I just need a reason to buy the 8-way octopus cable for it.

So for the cost of the Digi octopus cable, I can console-switch among 24 machines on 2 consoles, and hit 24 to 72 serial ports if you count those on the console-switched servers. Oh, I also have two 96GB 12-tape changers, a 48GB 6-tape HP changer, and a 40GB Exabyte Mammoth, but that's for a different "Ask Slashdot".

I have to say, there are times where I absolutely have needed KVM access to the Linux servers. I haven't setup any serial stuff yet, and my Amanda tape backup sometimes freaks out. I put SSHD as a respawn in inittab, but when a rogue app has exhausted all your memory and swap, direct console access via KVM (or I'm sure serial, too) is all you have. VNC wont do crap for you. And for hardcore firewall tweakers, we can all tell you we've locked ourselves completely out of the firewall at one time or another. I recently locked myself out of a remote box because when I upgraded SSH, I forgot to reset it to the non-standard port I listen on before I HUPped it. I loosened the firewall to listen on 22 just in case I pull that one again!

Okay I assume most of you here either a) have a KVM and either like or hate it, or b) don't have a KVM but might consider buying one but don't know which to buy. I'm going to tell you what you should look for. And by the way, Tom's guide (as usual) is dreadfully incomplete.

Some switches are mechanical, and others are electronic. Most electronic ones are better because they feature some kind of "emulation", meaning that when you switch off one machien to another, the machine you switched FROM still thinks the mouse and keyboard are connected when the OS polls the ports. On mechanical KVMs, they won't see anything and will sometimes b0rk.

However, not all emulating electronic KVMs are created equal. Belkin, Aten, Linkysys... they all have the same fundamental flaw: they have only one microprocessor trying to handle the emulation requirements of all the ports on the KVM.

One of the best switches you can possibly buy is a Raritan [raritan.com]. They have a dedicated microprocessor for each port.

I have tried using a Belkin Omnicube and an Aten Masterview with a very simple setup: one Windows XP box, and one FreeBSD or Linux box. With both switches, XP worked fine but with FreeBSD, you get (at best) errors from the kernel about how the mouse is out of sync (psmintr....). With Linux, I could only get it to work if I used a standard PS/2 Microsoft Intellimouse with the gpm and X driver settings set to "PS/2". If I wanted to use "IMPS/2", I had to kill and restart GPM every time I switched back to Linux. And neither Linux nor FreeBSD would even RECOGNIZE my Microsoft Optical Intellimouse with the USB-to-PS/2 converter on the end... although I reiterate that XP worked just fine.

Raritans, on the other hand, work flawlessly in any situation. They JUST WORK. I'm currently waiting for my new Raritan to arrive in the mail. They're slightly more expensive, but totally worth the money. And for those of you who are sysadmins for larger-scale projects, consider Raritans for those racks because they make rack-mountable KVMs with up to 12 ports... we used them at Internet2 [internet2.edu] and they work perfectly.

Compaq's [compaq.com] line of KVMs are rather nice for server managment, but come at a price. They have one that is a 2x8 KVM, aka 2 consoles and 8 ports. This is ideal for having one console in the server room, and one console in your office. And you can chain a KVM to each port, thus a total of 64 servers from one place.

Their newest idea is to use PCI cards and CAT5 to chain the systems togther. It uses the PCI power, and since the KVM is inside the server, it can save quite a bit of space and cable mess. And yes, they do pass through when the server is powered off.

Not the rolls royce of brands, nothing outside of "K-V-M" is switched BUT the unit (and the cables) produced no ghosting, it works be either pressing the putton on the front of doubletapping scroll lock and then the number of the terminal to switch to. It's also not terribly expensive.

I bought a Belkin 2 port unit a long while back. It required a wall wart (which sucked) and would periodically get hosed/stuck, which required a power cycle (aka pull it out and plug it in).

I decided I needed a 4 port, and decided not to go with the Belkin next up unit (for price as well as the problems with the 2 port). Browsing Fry's, I found a LinkSys 4 port self-powered (from keyboard power, and since one of my machines is never off except in a power outage, it stays on all the time) that had a good price (under or close to $200, and this was somewhere around or over a year ago) that works great.

It does have the cabling mess drawback; it's kind of flat lozenge shaped and has 2 system port sets on each side and the master ports out the back. But I haven't had any serious problems with it (any time I've gotten "no keyboard" it's been when I've switched right at the wrong moment in a boot). And it supports keyboard shortcuts to switch, so I don't even have to reach up to hit the button (maybe that's common now, but I was tired of whacking the button on the Belkin, and I'd only see this feature on "serious" kvm managers in data centers prior to getting this unit).

Currently I use the IOGEAR GCS124U - MiniView USB II - 4 Port USB KVM Switch (Hotkeys/OSD). For some reason when I'm in Mac OS 9 or KDE the scroll wheel is not detected. When I contacted IOGEAR support they told me it was a known issue that would be taken care of via a free chipset upgrade I could send the unit in for. The new chipset has been held up because of the terrorist attack and typhoons overseas. I highly recommend this unit but you may wish to check to make sure you're getting the latest revision. Strangely, Mac OS X does detect the scroll wheel just fine.

1) The keyboard switching doesn't work at all.
2) The keyboard repeat rate is LOCKED at 10.2 CPS under Linux. You cannot change the keyboard repeat rate with Linux at all.
3) The technical support people NEVER returned any of my calls of e-mails. They didn't help me at all.

Their switch is broken, and they don't give a shit that I had problems with it.

I used to use one of those mechanical four port kvm switches - but after a while (a couple of years) it started to get very flakey on me, so I decided to get something a little better. I wanted an active switch, but I needed at least four ports, hopefully more - but everywhere I turned, the price was INSANE for anything over two ports...

Then I decided to try Ebay...

I ended up bidding on an ATEN CS-106 [aten-usa.com] from a seller on Ebay, who had a few up for grabs as used equipment. I bid - and someone out-bid me. I was crushed, because my bid was $50.00, the person who had sniped me was $51.00. I noticed he had a zero rating, so I emailed the seller, and let him know that I was willing to pay was the winning bidder offered if he didn't come through (I had a rating of 40). The seller emailed me back, and said that he thought he had an extra, sans a power supply, and sold it to me - I sent him the money via paypal, and before he sent it, he said he found the PS and would throw it into the deal.

About a week later my KVM arrived - only a slight dent on the case gave any indication that it was used - other than that it was in perfect shape (even had the manual!). It was AT only (serial mouse, etc) - but for my needs perfect - 6 ports of perfection, for $50.00!!! I plugged it in using the cables I had already, and everything has worked great since. A simple CTRL-ALT-SHIFT-port#-RETURN to switch ports, other key combos to page through, or you can use the front panel switch. The case is built like a rock (pretty heavy steel construction).

I can only recommend this KVM - unless you have a need for a more expensive remote capable (ya know the kind, with Cat5 between the master unit and the remote), this one is it.

Oh, BTW - I should say that I got lucky - if you note from the link above, it still retails (MSRP) for $300.00, I have seen it used for about $200.00, maybe a little less. I got lucky for $50.00 - not sure how (of course, I also have this print buffer/10BaseT printer interface that normally goes for $400.00, picked it up used for $5.00 at a local electronics dump - so, maybe I have a knack for these deals...hmmm).

There had to be some ghosting at 1600x1200... so talk about that stuff then.

Why would there have to be ghosting at 1600x1200? Is it not possible that all those units were capable of supporting 1600x1200 and higher without any problems? I currently use one of the switches in the article, and use Cybex and Belkin switches at work all the time, and I run in 1600x1200 on nearly every machine I use. I've never had any ghosting problems from quality switches. Perhaps it could've been mentioned that there were no visual problems, but how interesting is that when that's the expected case?

If you use the cheap cables that came with some (a Belkin in my case) of the KVM's, you get ghosting. I run my boxes at 1600x1200 and had ghosting problems until I picked up some nice shielded video cables.

Quality of cabling has as much to do with it as the switch itself. If your cabling is too thin, or too long, or both, you'll obviously get ghosting. Modern KVM switches are rated for 1920x1440 or even higher. Most can handle 1600x1200@85Hz, or even 100Hz (I run 85Hz at work, 75Hz at home) without any visual artifacts, given good-quality cabling. With my IOGear, cables were provided, and of high quality imho. With the Cybexs and Belkins I've used, I needed separate cabling, but in each case used the bundled cables suggested for use by each company. I could certainly see one having a problem if s/he went out and bought just some cheap vga extension cabling rather than spending the $30 or so on decent cables.

I use a Dakota Scout kvm and used to have visible ghosting (bad) at 1600x1200, now with the same leads it's fine. The reason? I changed monitors- the video lead that comes out of the back of the monitor very often can't be changed so it's a good idea to try a friend's switch if you can.

BTW- avoid the old analogue type switches with rotary dials- they suck for quality and don't provide fake signals to the computers when not the currently selected one.

Do not meddle in the affairs of mice, for they are subtle and quick to anger.

No really, it could have been the mouse was "detecting" the wrong mode. I'm not sure exactly how those ps2/serial combo mice tell which protocol to use, but it could either be a connection in the adapter that is made (similar to a jumper), or something sent on bootup. Either that or I am totally off-base, but that seems like a likely explanation.